When I replace a 20w, 12v, G4 bulb in an accent light in a cabinet with a 10w, 12v, G4 bulb it just flashes once and goes out when I turn it on. The 20W bulb works fine but I have tried 2 different manufactures 10w bulbs and they do the same thing. The don't burn out since the flash once each time I turn them on. Is ther an internal thermal breaker in the bulb. Could the voltage be too high? Any comment would be appreciated.